The present invention relates generally to industrial control components such as fuse blocks and electrical disconnects as may be panel mounted, and in particular to a protective cover for these components.
Industrial control electrical equipment including components such as fuse blocks, electrical disconnects, and contactors, are typically mounted on a panel with interconnecting wiring run point-to-point between terminals on these devices. The mounting panel may be enclosed within a cabinet and the cabinet may have a door that may be closed to reduce the chance of accidental contact with the terminals and wiring of the components. The cabinet door may have an interlock, for example, working with the electrical disconnect to remove power from the components and wiring when the door is opened. However, often, an electrical interlock is not installed.
During testing and routine maintenance of the components and wiring within a cabinet, it may be necessary to have the cabinet door open while the wiring is live. For example, it may be desired to perform infrared thermography on the operating components to check for hot spots while power is applied. Alternatively, it may be necessary to probe voltages at points on the components while they are operating or to verify if fuses have blown. It may also be necessary to verify tightening torque at the termination points or electrical connections
In these situations, it is known that providing a secondary insulating cover over individual components to minimize the opportunity for inadvertent contact with electricity when the cabinet door is open is desirable. Such secondary covers may, for example, be molded of an insulating plastic or constructed of cardboard and may attach to the particular component by hooks or tabs or screws or other means.
One problem with these individual insulating covers is that they are not always replaced, particularly in circumstances where repeated access to the component is required. Removal and installation of the cover may be difficult requiring a removal of power and then a reapplication of power before the testing is performed. In components that may have multiple sizes as mounted on a panel, for example, an electrical disconnect with a trailing fuse block accommodating different sizes of fuses, providing covers is cumbersome and costly. Covers that are optional for a component, and thus purchased in small quantities, make special plastic molds impractical, yet inexpensive covers manufactured of paper or the like may not be suitable for the purpose or sufficiently durable.
The present invention provides a transparent cover that may be attached to individual panel-mounted electrical components and that may be readily manufactured from standard plastic sheet using simple folding operations. The cover has a door that may be opened for access to the components, simplifying such access and eliminating the problem of the cover being misplaced or removed entirely. The cover is suitable for components of varied sizes and shapes and having different available attachment points. A wide variety of cover plates may be manufactured in small quantities using stored computer-aided machining (CAM) files to cut the plastic sheet prior to folding.
Specifically, the present invention provides a cover system for electrical control components comprising an electrically insulating cover support detachably engaging structure of the electrical control component when the electrical control component is attached at a rear surface to a panel. The cover support presents a cover surface positioned in front of and having an opening providing access to electrically conducting elements of the electrical control component. An electrical insulating door is hingeably attached to the cover support to cover the opening when the door is in the closed position.
Thus, it is one object of the invention to provide a cover that reduces the chances that it will be misplaced or removed. The door may be opened for complete access while retaining attachment to the control component.
The electrically insulating door may be a transparent polymer material, for example, a polycarbonate such as Lexan.
Thus, it is another object of the invention to provide a cover that provides for visual inspection of the component prior to removal.
The electrically insulating cover support may also be a transparent polymer such as Lexan.
It is another object of the invention to provide improved illumination of the component and to simplify the construction and manufacture of the cover by making all parts of a single material.
The electrically insulating cover support and electrically insulating door may provide portions which together form a latch releasably holding the door in a closed position.
Thus, it is another object of the invention to allow the door to be stably held in a closed position reducing the chance of inadvertent contact with electrical components.
The latch and hinge may be integrally formed from the materials of the electrically insulating cover support and electrically insulating door.
Thus it is another object of the invention to provide a cover employing few parts (as few as two) and to allow all components of the cover to be, for example, insulating and transparent to provide the benefits of the material of the door and support.
The hinge may be at a side of the door to allow the door to open about a vertical axis.
Thus it is another object of the invention to provide a door which is naturally bi-stable remaining open or closed so as not to interfere with the inspection process nor require biasing springs or the like.
The invention may include an extensible shield attached to the door and vertically adjustable to provide an additional covering area of varying vertical extent. As before, the shield may be transparent such as manufactured from a polymer material like polycarbonate.
Thus, it is another object of the invention to provide a cover adaptable to a variety of different installation configurations of a particular control component.
The extensible shield may be held by electrically insulating connectors passing through at least one hole of a series of holes in the extensible shield and at least one hole in the door. The height of the extensible shield may be determined by selection of the hole of the series of holes in the extensible shield through which the insulating connectors are placed.
Thus it is another object of the invention to provide for a simple method of adjusting the size of the cover that may be performed in the field, for example, when a fuse block component is configured for different sizes of fuses.
The insulating cover support may detachably engage to the structure of the electrical component by means of side panels extending inward from the cover surface of the cover support about the electrical control component. In one embodiment, the side panels may include access cutouts.
Thus, it is another object of the invention to provide minimal interference with adjacent wiring needed for the control component.
The side panels may include holes engaging outwardly extending tabs on the electrical control component or may include inwardly extending fingers engaging holes in the electrical control component.
Thus it is another object of the invention to provide an attachment method that does not require the drilling or tapping of holes in the mounting panel such as would be difficult, time consuming, and raise the possibility of contaminating the control system with conductive metal fragments.
When holes are used in the side panels to attach it to the electrical control component, they may be adjacent to V-channels to align the side panels with the tabs on the control component prior to engagement of the holes with the tabs.
Thus, it is another object of the invention to allow simple engagement of the cover with the control component after it has been mounted on the panel and in situations of relatively low accessibility.
The electrically insulating cover may have legs extending inward from the cover surface about the electrical control component to abut a rear panel supporting the electrical control component to align the electrically insulating cover.
Thus, it is another object of the invention to provide a simple method of aligning the cover with the rear panel without requiring permanent attachment to the rear panel.
These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.